1. Field of the Invention
The invention relates to a process for analyzing a signal which is formed of a sequence of discrete amplitude values and to which portions with different phase angle contribute.
2. Description of Related Art
In the evaluation of the shape of signals to which portions with different phase angle contribute, it can be necessary to eliminate effects on the signal shape which are attributed solely to the phase shift of individual signal portions, i.e., the phase angle is to be eliminated from the signal shape. This is especially a problem when the relative phase angle of the signal portions is not known or not accurately known.
The primary object of this invention is to devise a signal analysis process which efficiently and easily eliminates effects attributed to phase differences of the signal portions from the signal shape.
This object is achieved in accordance with the invention by a process in which a reshaped signal is formed a sequence of discrete amplitude values to which portions with a different phase angle contribute, the sequence of amplitude values being changed such that the amplitude values or approximation values which have been brought near the amplitude values, follow one another in ascending or descending sequences according to their size.
It is advantageous in this approach for phase effects to be removed from the obtained reshaped signal which represents essentially an amplitude-sorted version of the original signal.
Sorting can be done in exact form, i.e., such that the amplitude value exactly preserved and only their sequence is changed. Generally however, it will be sufficient to carry out the sorting approximately, i.e., such that the amplitude values of the sorted signal do not correspond exactly, but only approximately to the original amplitude values; this can greatly reduce the computer cost. In doing so, the approximation values are preferably formed by assigning the same approximation value to all amplitude values which fall within a certain size class which covers a certain size range.
Preferably, sorting is performed by determining how many of each of the amplitude values fall into a certain one of the different size classes to which, according to the covered size range, a certain approximation value is assigned, and for each size class, beginning with the first free location, as many successive free locations of a field are described with the approximation value assigned to this size class as there are amplitude values which have fallen within this size class, the processing sequence of the size classes being determined according to the approximation values assigned to the respective size class in the ascending or descending direction.
Preferably, the signal is a processed signal for damage analysis on at least one cyclically moving machine element, especially of a roller bearing, which is caused by the movement of the machine element. The processed signal is preferably a signal portion with an adjustable period which has been separated from the originally received signal, the sorted signal being used for damage analysis. The period is preferably a period which is characteristic for damage of the machine element.
This process is especially suited, for example, for damage analysis from vibration signals of roller bearings, the signal extract being preferably the signal portions of the vibration signal which have been averaged over several periods and which have a periodicity which is characteristic for the damage.
These and further objects, features and advantages of the present invention will become apparent from the following description when taken in connection with the accompanying drawings which, for purposes of illustration only, show a single embodiment in accordance with the present invention.